Fault shutdown slaves are the salve rails of the faulted rail. Each rail can have its own fault slaves rails (as shown in Figure 18). When a fault occurs on the master rail, if its response is to shut down, all slave rails are also shut down. If retries are specified for the master rail, the slave rails remain running until all retries are exhausted. For the UCD90120 and UCD90124 devices, the slave pages are shut down in the same way as the master page is (immediately or soft stop). For devices other than the UCD90120 and UCD90124, the slave pages are shut down using sequence off dependencies and TOFF_DELAY. The slave pages do not perform any retries during the fault slave shutdown. After being shut down, slave rails are latched off as if they had experienced the fault. A status bit is set in their MFR_STATUS word indicating the reason they are latched off. If a re-sequence is enable at fault response of master rail, the fault shutdown slaves will be re-sequenced along with master rail.
If the fault response of master rail is set to ignore and continue operation, the fault shutdown slaves are meaningless.
For more FAQ please check the following document.
UCD90xxx Family Frequently Asked Questions and Answers
UCD9090 UCD9090A UCD90120 UCD90120A UCD90124 UCD90124A UCD90160 UCD90160A UCD90240 UCD90320 UCD90320U